1. Field of the Invention
The present invention relates broadly to the transporting of sheet materials and, more particularly, to an improved package for shipping and storing a stack of individual automotive windshields or other curved glass articles.
2. Description of the Prior Art
Composite packages employing reusable racks and adjustable tie-down straps have been previously used for shipping fabricated curved glass sheets as shown, for example, by commonly assigned U.S. Pat. Nos. 3,147,860, to J. S. Kean, Sr., and 3,809,234, to J. F. Kurick. As shown in these disclosures, it was formerly common practice to merely anchor individual banding straps at their opposite ends to the rack frame and secure them over the stack of articles by buckling their respective free ends together. In such banding arrangements, a plurality of articles are simply stacked on their edges in upright position in the shipping rack and the individual glass articles of the group are separated from each other, for example, by sheets of unanchored cushioning material to prevent their marring and/or breakage in transit. Usually two individual, spaced apart banding straps are employed and each is anchored at the bottom back of the rack, passes over the top edges of the glass articles, then vertically downward over the outer surface of the stack, and is anchored at the front bottom edge of the rack. Each strap is provided with a buckle arrangement to tension the straps for holding the stack of glass articles firmly on the rack.
However, to merely secure the stack of glass articles on the rack in this manner may create certain problems, among which are the following: (1) Because of stretch or creep inherent in the material employed in the banding straps, tensioning of the individual straps normally result in non-uniform pressures being applied to the stack of glass articles; (2) It has been found in devices of this type that when individual straps are employed they can only be tensioned by application of about 25 foot-pounds of torque to secure the stack of glass sheets to the rack and that additional torquing results in breakage or cracking of some of the glass articles; and (3) After initial tensioning, the individual banding straps tend to loosen due to the aforementioned or elongation inherent in the strap material as well as slippage of the fastening devices. As a result of the reduced tension, the stack of glass articles exerts a considerable force on the banding straps when the entire package is subjected to jarring forces or impact produced by rapid changes in momentum of the transporting vehicle. These forces accelerate still further loosening of the banding straps by increased stretching of the straps and/or slippage of the fastening devices. This loosening of the banding straps may allow shifting of the stack of glass articles on the rack and result in marring and breakage of the individual windshields. Since each windshield is completely fabricated when shipped, most including a radio antenna and connecting device, damage to any portion of the unit results in loss of the entire unit and hence involves a substantial economic loss. Thus, it is desirable to tie the stack of glass articles to the rack in a more secure manner by providing a banding arrangement which applies the securing load to the glass article uniformly and with greater loading pressure than has heretofore been possible so that when any stretching or slippage of the banding strap occurs, the articles remain tightly held, thus preventing any movement of the articles relative to the rack. It has been found that the shipping package of the present invention with a novel unitized adjustable banding arrangement provides greater protection during handling and shipping of the glass articles than was heretofore possible.